Centrifugal clutch



Dec. 12, 1950 H. G. KIRKPATRICK CENTRIFUGAL CLUTCH Filed Aug. 2o, 194e 3 Sheets-Sheet l i Q- d Dec. 12, 1950 H. G. KIRKPATRlcK CENTRIFUGAL CLUTCH 3 Sheets-Sheet 2 Filed Aug. 2o, 194e lll/1111111111111 H. G. KIRKPATRICK CENTRIFUGAL CLUTCH Dec. 12, 195o 3 Sheets-Sheet i5 Filed Aug. 20. 1946 H mw V M i ,4 f Y z Patented Dec. 12, i950 zbUINIIlISrD PATENT OFFICE Herwalil Gordon Kirkpatrick, E dgeclif, meer Sydney, NeFWrSeuth Wales, Australia ys claims. (o1. 19e-1505 'become disengeee from the Imm for a. preletermine :speed Sli-as @been reached when f degree l-consideif-bly lower :the Vezine-"ee ef Veniv ttonimweeredetefmmeefweedismeaehe'mn 5,7,

the shoe or shoes are released to smoothly engage the meinber- =to *be fcintehed air-1d r1after la governed driver; while during deceleration the vshoe or sh'oes will be maintained in driving engagernent, and. feontinue to transmit the :full torque #of he driver vuiitil ek'ny :low predetermined :speed Aris ouslsr fdisenyaee.

More Js'pecicallly fcbnsidereel, e, `crut-ch sa-ecardin'g im erre .invention fcomprifses 'a plurality i'of shoes mounted for outward wmovement under centrifugal acbi'on df e driving member sand a:

vzei in:l 'associated with each snee :and capable :of lim ed L/eubvvzmrz movement fender centrifugai aerien liniiependently fof the oufwar movement of 'fone snoei; 'resiiien'ft means :for exampe 'e compression spring for :springs between each shoe 'and Aits f'as'soei'ated Weight fand m'eans for rrelezais4 ingr the shoes 'with theii lessociited weiglftsz,

meens forreleasably homing the Wei'glarbs fiosiizion with gthe springs fender `rcoiirileressi'on ereby when the .speed decreasing the leo'nlti trans I ittim'g tine fuii tom-ue the driver'my Geni-,singel @eroe raind Aspring pressure uni-r1 n me 3 determined-lower speed reiche '-Whentheeslfr'oes.

Afie 13o be niainidined "in engagement fand In the 'accompanying drawings clutches according to theilnfvntion':

`al,'61111179111elecor`ciif-i*g to invention,

"Figure i2 fa `seais-ritmi eleve-tion cn whe :grof-Figurer,

Fre-ere 3 is a wiew similar ro Fi'gme 1 .showing Figure 4 is fa sectiona Aeleifaiti'on en the line 'Figli-1re f5 is la View simile; 2te `figure .1 showing. ,afnemer-medina efeiueeheee "mg-ure y6 is a sectional feievation' en me une.

fofegurefif n Referring Vtol'igiires 1 amil 2 yen wthira'dial .cirivn'gpms 122. FSHdwLiiy 'mounted onfeach pin is a sleeve Wardly 'extending yMange.

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g :geen Saa,

Slidable on 'each lsleeve 2| is a weight 22, having a central bore slidably to receive the sleeve 2| and may have inwardly convergent end faces. Each Weight has transverse bores 23 therethrough in each of which is slidably mounted a spacer 24 each end of which maybe formed as a vconcave spherical surface. Each spacer is shorter than the length of its bore so that the latter at each end can partially accommodate one of a pair of Y anti-friction abutment balls 25, 26. As Will be seen in Figure 2 nearly one half of each ball projects beyond the plane of the adjacent side of the weight;

Each Weight also has cylindrical holes Z'I, spaced on either side of the axis of its sleeve 2| and each hole 21 receives a compression spring 28 which bears at one end on the bottom of the hole and at the other end on the inner plane surface Vof the brake shoe. Pins 3| and 32 projecting downwardly from the shoes into the upper ends of the springs may be provided to prevent lateral displacement of the shoes I9.

The hub I has a pair of outwardly extending radial flanges IIa, IIb, having their inner surfaces spaced from the sides of the Weights 22 so as not to interfere with inner and outward movements of the latter. Mounted on each side of the hub II are side plates I3, I4, having secured against their inner surfaces annular plates 29, 30, which have an annular projection V- shape in cross section providing inner ramp surfaces I5 and I6 and outer ramp surfaces I'I and I8 for the anti-friction balls.

Each side plate has a plurality of pairs of guide pins 34 and 35, each of which projects through the adjacent hub flanges I Ia and I Ib, so that the side plates I3 and I4 rotate with the hub II. Each pair of guide pins 34, 35, has anchored thereto the respective ends of a tension spring 33 and it will be seen from Figures 1 and 2 that these springs 33 extend across the face of the hub I I and between the pins I2.

In operation the shaft I is rotated by starting the engine or other prime mover, when the hub II 'commences to drive the clutch and as the speed increases centrifugal action is first resisted bythe tension springs 33 but on further increase of speed the increase of centrifugal force acting on the shoes I9 and weights 22 causes them to commence to move outwardly together relatively to the pins I2. At the same time the abutment balls 25, 26, ride up the inner ramp surfaces I and I6 forcing the side plates I3, I4 and guide pins 34 and 35 outwardly and before the balls have reached the crests of the ramps the shoes are uniformly in engagement with the inner surface of the drum 5. As the speed further increases the weights continue to move uniformly outwardly relatively to the shoes compressing the springs 28 which act on the shoes to press the latter more firmly into engagement with the inner surface of the drum 5 and when the balls overrun the crests of the ramp the side plates are returned by the springs 33 to their inward positions, when springs 28 are compressed to their fullest extent and the weights in positive contact with the shoes which are then engaged with- 4 out slip with the drum 5 and capable of transmitting the full torque of the driver.

When the speed of the shaft I0 and hub II ldecreases to a loW predetermined limit the decrease of centrifugal force permits the springs 28 to react on the weights and at the same time continue to exert outward pressure on the shoes. As the resistanceof the springs 33 is overcome the side plates I3 and I4 again In'ove outwardly, the balls riding on the outer surfaces I'I and I8 of the ramps. After the balls have passed over the crests of the ramps the springs 33 act to force the plates I3 and I4 inwardly, assisting the springs 28 in forcing the weights further inwardly until they act upon the flanges of the sleeves 2| so as to instantaneously and uniformly disengage the shoes with the drum 5 or clutched member.

In a modied form of construction shown in Figures 3 and 4 Va pairof diaphragms I 3a and I4a secured to driving hub II by bolts 39ais substituted for the side plates I3 and I4, guide Y pins 34 and 35 and tension springs 33 of Figures l and 2.

In a further modified form of construction shown in Figures 5 and 6 a compression spring 24a between each pair of abutment balls 25, 26,`

substitute the spacers 24 and springs 33 of Figures 1 and 2 and the side plates I3 and I4 areV and adapted to be rotated by said rotatable mem,

ber, a weight mounted in relation to the rotatable member so as to be driven outwardly by centrifugal force when the rotatable member is rotated, resilient means interposed between the' 3 weight and the clutch member and acting wheny compressed therebetween to provide at one side the force for engaging the clutch member with the member to be clutched and at the other side a force ,for opposing the centrifugal force exerted. by the weight and means whereby when the r e silient means has been compressed to a predetermined extent an additional force, independent of the centrifugal force and acting in the direction opposing release of the compression of the resilient means, is brought to bear onV the resilient means, said means comprising an abutment onI the Weight engaging a spring diaphragm having inner and outer annular ramp surfaces on the side adjacent the weight and convergent towards the weight.

2. In a clutch a rotatable member, a member Yto be clutched to said rotatable member, a clutchv member for engaging said member to be clutchedv and adapted to be rotated by said rotatable member, aweight mounted in relation to the rotatable member so as to be driven outwardly by centrifu gal force when the rotatable member is rotated, resilient means interposed between the weight,

and the clutch member and acting when compressed therebetweento provide at one side the force for engaging the clutch member with thev member to be clutched and at the other side a force for opposing the centrifugal force exerted by the weight and means whereby .when the resilient means has been compressed to a predetermined t said-means kcomprising an abutment on the-,weight i cengaging a side uplate axially movable on the clutch `against spring pressure and having inner andouter `annular ramp surfaces on the Vside Sad- 4jacent the weight and convergent towards 'the weight.

3. A frictionclutch comprisingea plurality of shoes mounted on a rotary driving member for outward [movement under centrifugal for-ce into frictionalfengagementwitha amber to bei-driven,

weights associatedwiththeshoesfispringsfbetween Y the weights and shoes, the weights being capable of outward movement relatively to the shoes un.- der centrifugal force to press the shoes through the medium of the springs, against the member to to be driven on acceleration of the driving member to a speed above the speed at which the shoes engage the member to be driven, and means carried by the driving member and which co-operates with means carried by the Weights releasably to hold the weights from inward movement relatively to the shoes until on deceleration of the driving member it rotates at a lower speed than that at which the shoes move outwardly under centrifugal force into engagement with the driven member, said means carried by the driving member comprising a pair of spring diaphragme each secured by its central portion to the driving member and having annular converging ramp surfaces and abutments carried by the weights and engaging the diaphragms.

4. In a friction clutch a rotatable member, a member to be clutched to said rotatable member, a clutch member for engaging said member to be clutched and adapted to be rotated by said rotatable member, a weight mounted in relation to the rotatable member so as to be driven outwardly by centrifugal force when the rotatable member is rotated, resilient means interposed between the weight and the clutch member and acting when compressed therebetween to provide at one side the force for engaging the clutch member with the member to be clutched and at the other side a force for opposing the centrifugal force exerted by the weight, and means for providing anvadditional inward force on the weight over a certain Y range of its movement so that the resilient means is not compressed until a predetermined speed of revolution of the rotatable member is reached whereupon the clutch member is smoothly engaged with the member to be clutched by a gradually increasing compression of the resilient means over a predetermined range of speeds of revolution and at a predetermined lower speed of revolution the clutch member is rapidly disengaged from the member to be clutched by a rapid inward movement of the weight releasing the compression of the resilient means.

5. In a friction clutch a rotatable member, a member to be clutched to said rotatable member, a clutch member for engaging said member to be clutched and adapted to be rotated by said rotatable member, a weight mounted in relation to the rotatable member so as to be driven outwardly by centrifugal force when the rotatable member is rotated, resilient means interposed between the weight and the clutch member and acting when compressed therebetween to provide at one side the force for engaging the clutch member with the member to be clutched and at the other side a force for opposing the centrifugal force exerted hyftneiweignt,fandmeansfforprovidnganiauie tional inward iforceon the weight over Ta fceiitain range of its movement so that the clutchlmember ish'eld disengaged fromltlie member tobefclutched `until larl'predetermined Speed of `revolution ofthe iitaitable member I is reached whereupon l"the clutch :member is .smoothly engaged with :the member to be1 clutched byla ygradual1y increasing compression ofthe Avresilient means over 'a prede termine'd range for Ispeeds cf :revelation fand at a predetermined lower speed of revolution Fthe clutch lmember .iis lrap'idly .disengaged from the member to be clutched by a rapid inward movement of the weight'relea-sing'fthecompression of fthe resilient means the rapid inward-movement continuing while the weight ypositivelyengages the clutch member to withdraw it from contact with the member to which it was clutched.

6. In a friction clutch a rotatable member, a member to be clutched to said rotatable member, a clutch member for engaging said member to be clutched and adapted to be rotated by said rotatable member, a weight mounted in relation to the rotatable member so as to be driven outwardly by centrifugal force when the rotatable member is rotated, resilient means interposed between the Weight and the clutch member and acting when compressed therebetween to provide at one side the force for engaging the clutch member with the member to be clutched and at the other side a force for opposing the centrifugal force exerted by the weight, and spring-loaded ramp and abutment means for providing an additional inward force on the weight over a certain range of its movement so that the resilient means is not compressed until a predetermined speed of revolution of the rotatable member is reached whereupon the clutch member is smoothly engaged with the member to be clutched by a gradually increasing compression of the resilient means ov-er a predetermined range of speeds of revolution and at a predetermined lower speed of revolution the clutch member is rapidly disengaged from the member to be clutched by a rapid inward movement of the weight releasing the compression of the resilient means.

'7. In a friction clutch a rotatable member, a member to be clutched to said rotatable member, a clutch member for engaging said member to be clutched and adapted to be rotated by said rotatable member, a weight mounted in relation to the rotatable member so as to be driven outwardly by centrifugal force when the rotatable member is rotated, resilient means interposed between the weight and the clutch member and acting when compressed therebetween to provide at one side the force for engaging the clutch member with the member to be clutched and at the other side a force for opposing the centrifugal force exerted by the weight, means for providing an additional inward force on the weight over a certain range of its movement so that the resilient means is not compressed until a predetermined speed of revolution of the rotatable member is reached whereupon the clutch member is smoothly engaged with the member to be clutched by a gradually increasing compression of the resilient means over a predetermined range of speeds of revolution and at a predetermined lower speed of revolution the clutchmember is rapidly disengaged from the member to be clutched by a rapid inward movement of the weight releasing the compression of the resilient means and means whereby when the resilient means has been compressed to a predetermined 7 extent an additional outward force is provided acting on the Weight over a certain range of its movement.

8. A clutch as claimed in claim 6 in which the clutch member is slidably mounted by means of sleeves on pins projecting from the rotatable member and the weight is slidably mounted on the sleeves the inner end of each sleeve having an outwardly extending flange which limits the inward movement of the weight in relation tothe /10 sleeves. l

HERWALD GORDON KIRIGATRICK.

REFERENCES CITED The following references are of record in the 15 le of this patent:

UNITED STATES PATENTS Number Number Date Name Bendl Sept. 12, 1916 Welch Feb. 20, 1934 Nilsson et al. Mar. 24, 1936 Kreis Jan. 19, 1937 Keller July 18, 1939 Keller Aug. 29, 1939 Keller Sept. 26, 1939 FOREIGN PATENTS Country Date Switzerland Mar. 1, 1935 Germany Jan. 23, 1912 

